Week 16 System Integration

This week, I focused on the system integration of my final project The Honor Tree, which is an interactive classroom display that celebrates students’ achievements.

assignment:

• Design and document the system integration for your final project.

1.1 System Overview

The Honor Tree consists of multiple components working together:

• Input: Hall sensors detect 3D-printed apples with embedded magnets.
• Output: WS2812B LEDs light up and DFPlayer Mini plays a celebration sound.

• Controller: A XIAO-ESP32-C3 serves as the central microcontroller.

• Structure: A multi-layer tree made from laser-cut cardboard and a felt board holds the electronics.

1.2 Bill of Materials

Component	Quantity	Unit Price (RMB)	Notes
PLA Filament	93g	--	Provided by FabLab Formshop
3mm Corrugated Cardboard	3 pcs	--	Laser-cut tree structure
9mm Felt Board	1	21.8	Tree background
Seeed XIAO-ESP32-C3	1	34.05	Main microcontroller
WS2812B RGB LEDs	8 pcs	17.36	Light up apples
A3144 Hall Sensor	8 pcs	17.6	Detect magnetic apples
Neodymium Magnets	8 pcs	3.3	Inside 3D-printed apples
DFPlayer Mini	1	39	Plays sound effects
Speaker (3W 8Ω)	1	4.12	Connected to DFPlayer
SD Card (8GB)	1	3.7	Stores MP3 files

1.3 Circuit and Electronics Integration

I designed a custom PCB using EasyEDA based on the XIAO ESP32-C3,A total of 8 pins are required for the Hall sensors and 1 for the LED, plus two pins for the mini player, along with power and ground pins. No additional pin expansion board is needed for the Xiao.

Design Process

Click Place - Component

Enter the component name in the search box and select the model you purchased

Click the mouse to place the component on the canvas

Click Place - Add online tag

Connect one by one

Enter the tag name

Finish the design

Design - Convert schematic to PCB

Arrange the components

Routing - Single Track Routing

line Wiring

Click Place - Frame - Panel Frame

Board Frame

Place - Text

Input Text

Design and Manufacture

PCB board

1.5 Structure Integration

• In the first layer, use screws to attach the Hall sensors and LED lights to the felt board.

• In the second layer, laser-cut gray corrugated cardboard to form the tree trunk. This layer encloses the wiring from the first layer. Be sure to design openings so that the sensors and LED lights align with the apples, enabling the switch sensing function.

• For the third layer, laser-cut green corrugated cardboard to represent the tree leaves. Make sure to include slots that fit the size of the apples, allowing the 3D apples to be hung securely so that the magnets inside can trigger the Hall sensors.

• Finally, laser-cut a pink corrugated cardboard music box, embed the speaker inside it, and attach it to the lower right corner.

1.6 System Test & Result

When a student attaches their apple:

1. The Hall sensor detects it.
2. The matching LED lights up.
3. A “Great job!” message plays from the speaker.

This provides immediate feedback and motivates students through interactive celebration.

Here is my first version — an Honor Tree made of a wooden box. Since the surface area was relatively small, I upgraded to the second version to enhance the visual effect.

Reflection

Integrating all the parts was challenging yet rewarding. Aligning structure and electronics required multiple iterations. The result is a beautiful and meaningful classroom interaction tool that helps students feel recognized and proud of their efforts.

Design files

Code2.1 for this week Code2.2 for this week Code2.3 for this week Code2.4 for this week Code2.5 for this week